Meeting Abstract
In species that form dominance hierarchies, there are often opportunities for low-ranking individuals to challenge high-ranking ones, resulting in a rise or fall in social rank. How does an animal detect, process and then respond to these social transitions? The African cichlid fish, Astatotilapia burtoni, provides an ideal model to examine how changes in social rank rapidly impact an individual’s behavior, physiology, and brain. Males form hierarchies where a few brightly colored dominant males defend territories and spawn with females, while the remaining males are subordinate, drab colored, do not hold a territory, and have minimal reproductive opportunities. These social phenotypes are plastic and reversible, meaning that individual males may switch between dominant and subordinate status multiple times within a lifetime. When the social environment is manipulated to create males that either ascend (subordinate to dominant) or descend (dominant to subordinate) in rank, there are rapid changes in behavior, circulating hormones, and gene expression levels in the brain that reflect the direction of transition. For example, within minutes, males ascending in status show bright coloration with a distinct eye-bar, increased dominance behaviors, higher plasma levels of sex-steroids and gonadotropins, and activation of brain nuclei in the social behavior network. These males also show rapid changes in neuropeptide and steroid receptor levels in the brain, as well as in the pituitary and testes. Also within minutes, descending males show faded body coloration, decreased dominance behaviors, increased subordinate behaviors, and higher circulating levels of cortisol. Collectively, this work highlights how the perception of similar social cues that are opposite in value are rapidly translated into adaptive behavioral and neuroendocrine changes to promote survival and reproductive fitness.
